GB1572780A - Forging press - Google Patents

Description

(54) A FORGING PRESS (71) We, KAWASAKI YUKOH KABUSHIKI KAISHA, a Japanese company of 9-3, Mihori, Takasago, Hyogo, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a forging press and is more particularly though not exclusively concerned with a forging press for use in stamp forging when strict control of dimensions of the forging is required.

Hydraulic forging presses equipped with mechanical driving means are known. However, in such a conventional forging press, any device for altering the distance through which the ram is to fall (hereinafter called the impact fall) is based upon the principle that the impact fall can be altered by increasing or reducing the quantity of oil between an upper ram and a lower ram, i.e. forcing oil into the cylinder from the outside or discharging it to the outside. Such conventional devices are only effective in so-called rough forging techniques which are primarily used to produce work-hardening in the material being forged. However, in precision forging or stamp forging the use of such devices is beset with problems.When precision in dimensions is required, a first impact fall is designated, for example, at a metres and a second one at (a - 0.3) metres using a conventional forging press as described above, it is necessary to calculate a volume in the cylinder corresponding to a fall distance 0.3 metres of the press ram and to feed oil from outside into the cylinder in a quantity exactly corresponding to said calculated volume. It may be easily understood that such calculations cannot be achieved in as short a period as is desirable. For these reasons conventional forging presses have hitherto rarely been used for precision forging or stamp forging.

According to the present invention there is provided a forging press comprising an elongate ram housing having an upright part of said chamber, means for mechanically imparting movement to said pump ram, a press ram slidably positioned in a lower part of the said chamber spaced apart from said pump ram such that a cavity of adjustable volume is defined therebetween, means for supplying a controlled amount of oil to said cavity, the oil in said cavity being for transmitting motion of said pump ram to said press ram under certain conditions, an adjustable stop means provided on the outside of said housing in alignment with a laterally protruding member on the press ram, which stop means is adapted for controlling the highest point reached by the press ram, and means connected to said oil supply means for restoring the press ram to said highest point.

When using a forging press according to the present invention, it is possible to fix a new impact level defining the height of the impact fall from outside the press by adjusting the stop means and then feeding or discharging oil into or from the adjustable cavity in that quantity required for operating with the new impact level.

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made by way of example, to the accompanying drawings in which: Figure 1 shows mainly in vertical section a forging press according to the invention, equipment associated therewith being shown schematically; Figure 2 shows one form of a detail of Figure 1 and to a larger scale; Figure 3 shows another form of the detail of Figure 1 to a larger scale; and Figure 4 shows in plan view a portion of the detail of Figure 3.

In Figure 1, the numeral 1 indicates a hous ing of a forging press, the housing definin upper and lower cylinder portions 2a and which are separated by a cavity 11 of greater cross-section. A pump ram 3 and a press ram 4 are inserted in the upper and lower cylinder portions 2a and 2b respectively. In an upper part of the housing 1 is provided a crank shaft 7 connected by a connecting rod 8 to a flywheel 6 which is driven by a motor 5 to lift and lower the pump ram 3 through a fixed distance. Numeral 9 indicates a laterally protruding member fixedly attached to the press ram 4 and constrained against downward motion by the return cylinder 10 through a push-up ram 10a. Oil in a tank 15 provided inside the upper part of the housing is fed into the cavity 11 through a pilot operated check valve 12 and ducts 13 and 14.The numeral 16 indicates a relief valve which controls the maximum pressure of oil in the duct 14. The check valve 12 is usually kept open by pressurized oil in a pressure accumulator 18 through a changeover valve 17. The numeral 19 indicates a pump for feeding oil into the pressure accumulator 18, and 20 designates a duct connecting the pressure accumulator 18 to the return cylinder 10.

When the check valve is open (as shown in the drawing), and the motor 5 is energized, the pump ram 3 reciprocates a fixed distance but the press ram 4 remains at its highest position and is not lowered against the oil pressure in the return cylinder 10 owing to flow of oil between the cavity 11 and the tank 15 through the ducts 13 and 14.

When a push-button (not shown in the drawing) is depressed, a solenoid 17a of the changeover valve 17 is actuated, and therefore the changeover valve 17 is moved from the position shown in the drawing to its other position which consequently closes the check valve 12, traps oil in the cavity 11 and duct 14, and allows transmission of the reciprocating motion of the pump ram 3 to the press ram 4 through oil in the cavity 11. Hence material to be forged may be formed by the bottom surface 4a of the press ram 4. A projection 21 is provided on the fly-wheel 6 in such a position that it strikes a limit switch 23 before the pump ram 3 reaches its highest position. The solenoid 17a is adapted to be actuated by a signal generated when the limit switch is depressed by impact of the projection 21.Hence the time at which the check valve 12 is closed is accurately determined and the press ram 4 falls through a fixed distance. When output of the press ram exceeds that specified during operation, the relief valve 16 relieves pressure in the duct 14 thus preventing overloaded operation. If continuous operation of the press with a fixed impact level is required, the check valve is kept closed. If, however, single cycle operation of the press is desired, another limit switch 22 is provided which, upon actuation by the projection 21 during rise of the pump ram 3, demagnetises the solenoid 17a which controls the changeover valve 17.

Stop means 24 is provided secured to the outer surface of the housing 1. The end surface 25 thereof is disposed to face the upper end surface of the push-up ram 10a which is fixed to the one end of the member 9 and moves with the press ram 4. Various types of known apparatus may be used as the stop means to adjust dimension 'd' which defines the position of the end surface 25, i.e. where the stop means 24 and the push-up ram 10a come into contact with each other. However, referring to Figure 2, a preferred arrangement for controlling the height of said stop means will be described.The figure shows a pulse motor 26 whose shaft carries a gear 27, an internally threaded intermediate gear 28 revolved by the gear 27, an elongate member 29 in threaded engagement with the internal threading of the gear 28 and driven thereby, the elongate member 29 being positioned in a housing 31 and connected to a servo arrangement having oil inlet and outlet ducts 32 and 33. A lower section 30 of the servo arrangement provides the aforesaid surface 25. The position of the surface 25 can be adjusted with high precision and in a relatively short period of time by adapting the pulse motor 26 to turn at a specified number of rpm. Hence the distance 'd' can be set accurately.

Figure 3 shows another arrangement for controlling the height of said stop means. A circular member 34 which varies uniformly in thickness from one edge region to a diametrically opposed edge region is interposed between a stop 35 and the push-up ram 10a. The circular member 34 is rotated by a gear 37 having a common axis with the member 34. The gear 37 is turned by a rack 38 driven by a hydraulic pressure cylinder 39. The highest point of travel of the press ram 4 is therefore adjusted by inserting a wedge between the stop member 34 and a linear wedge may be employed in association with suitable displacement means therefor.

In Figures 1 to 3, the numeral 40 indicates a switch provided adjacent the position of the upper end of the push-up ram 10a. When a new impact level lower than the already set level is required, an adjustment is made so that the dimension 'd' is reduced by a known amount by operating the stop member height controlling arrangement of Figure 2 or 3, depending upon a signal corresponding to loss of contact between the switch 40 and the controlling arrangement after the press ram 4 has started to move downwards. When the press ram 4 starts rising again under such adjusted conditions, it continues to rise to a position designated by the stop means, and afterwards the pump ram 3 alone continues to move upwards the mechanically fixed distance to the dead point.As a result, the volume of the cavity 11 increases and suction force generated thereby opens the check valve 12 so that as much oil as is required may be drawn into the cavity 11 from the tank 15 through the opened check valve 12.

When the pump ram 3 starts falling, the check valve 12 automatically closed and the downward stroke of the pump ram 3 is transmitted to the press ram 4. The forging press is now ready to operate with the newly designated impact level. Similarly, when a new impact level higher than the present one is required, sufficient oil will be discharged from the cavity 11 for the quantity of oil remaining to correspond to the amount required for operating the forging press with the new impact level. As the pump ram reaches the top of its stroke it actuates the limit switch 22, and the check valve opens.

Oil is discharged until the limit switch 23 is actuated and the check valve closed. After this the press ram may rise slightly as the distance 'd' has been increased. Any significant rise in oil-pressure in the cavity 11 and duct 14 will then be alleviated by the relief valve 16. The press ram stops rising when the push ram 10a comes into contact with the section 30 or member 34. The forging press is now ready to operate with the newly designated impact level.

WHAT WE CLAIM IS: 1. A forging press comprising an elongate ram housing having an upright cylindrical chamber, a pump ram slidably positioned in an upper part of said chamber, means for mechanically imparting movement to said pump ram, a press ram slidably positioned in a lower part of the said chamber spaced apart from said pump ram such that a cavity of adjustable volume is defined therebetween, means for supplying a controlled amount of oil to said cavity, an adjustable stop means provided on the outside of said housing in alignment with a laterally protruding member on the press ram, which stop means is adapted for controlling the highest point reached by the press ram, and means connected to said oil supply means for restoring the press ram to said highest point.

2. A forging press as claimed in claim 1, wherein said means for mechanically imparting movement to said pump ram comprises a flywheel driven by a motor, which flywheel is connected by a crankshaft and a connecting rod to the pump ram such that the pump ram is continuously raised and lowerd through a fixed distance during a forging operation.

3. A forging press as claimed in claim 1 or 2, wherein said oil supply means comprises a check valve connected by duct means to said adjustable cavity and to a reservoir, and a changeover valve which, upon actuation, shuts said check valve.

4. A forging press as claimed in claim 3, wherein said changeover valve is magneti cally actuated.

5. A forging press as claimed in claim 3 or 4, further comprising a projection formed on said flywheel adapted to actuate said changeover valve by contact with a first limit switch, the projection being positioned on the fly-wheel such that it contacts the first limit switch before the pump ram reaches its highest position.

6. A forging press as claimed in claim 5, further comprising a second limit switch for deactuating the changeover valve and opening the check valve upon contact with said projection.

7. A forging press as claimed in any preceding claim, further comprising means for effecting reciprocating motion of the stop means lengthwise of the housing and relative to said laterally protruding member, this means comprising a pulse motor, a geared shaft driven, in use, by the motor, a geared wheel meshing with the geared shaft and comprising an internally threaded intermediate member which is, in use, revolved by the gear, connected to a pusher member of a servo arrangement carrying said stop means whose position is governed by the extent of rotation imparted to the intermediate member.

8. A forging press as claimed in any one of claims 1 to 6, wherein said stop means includes a member whose thickness varies from one edge region to an opposite edge region acting on a further part of the stop means and means for displacing said member in such manner that it causes said displacement of the relative distance between said stop means and said laterally protruding member, in accordance with the thickness of the portion of the said member acting on said further part of the stop means.

9. A forging press as claimed in claim 8, wherein said member is of circular from varying uniformly in thickness from one edge region to a diametrically opposed edge region and the means for displacing said member comprises a geared wheel carrying said member, a rack engaging the geared wheel and means for imparting linear motion to the rack.

10. A forging press, substantially as hereinbefore described with reference to, and as shown in Figures 1 and 2, or Figures 1, 3 and 4 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. to move upwards the mechanically fixed distance to the dead point. As a result, the volume of the cavity 11 increases and suction force generated thereby opens the check valve 12 so that as much oil as is required may be drawn into the cavity 11 from the tank 15 through the opened check valve 12. When the pump ram 3 starts falling, the check valve 12 automatically closed and the downward stroke of the pump ram 3 is transmitted to the press ram 4. The forging press is now ready to operate with the newly designated impact level. Similarly, when a new impact level higher than the present one is required, sufficient oil will be discharged from the cavity 11 for the quantity of oil remaining to correspond to the amount required for operating the forging press with the new impact level. As the pump ram reaches the top of its stroke it actuates the limit switch 22, and the check valve opens. Oil is discharged until the limit switch 23 is actuated and the check valve closed. After this the press ram may rise slightly as the distance 'd' has been increased. Any significant rise in oil-pressure in the cavity 11 and duct 14 will then be alleviated by the relief valve 16. The press ram stops rising when the push ram 10a comes into contact with the section 30 or member 34. The forging press is now ready to operate with the newly designated impact level. WHAT WE CLAIM IS:

1. A forging press comprising an elongate ram housing having an upright cylindrical chamber, a pump ram slidably positioned in an upper part of said chamber, means for mechanically imparting movement to said pump ram, a press ram slidably positioned in a lower part of the said chamber spaced apart from said pump ram such that a cavity of adjustable volume is defined therebetween, means for supplying a controlled amount of oil to said cavity, an adjustable stop means provided on the outside of said housing in alignment with a laterally protruding member on the press ram, which stop means is adapted for controlling the highest point reached by the press ram, and means connected to said oil supply means for restoring the press ram to said highest point.

2. A forging press as claimed in claim 1, wherein said means for mechanically imparting movement to said pump ram comprises a flywheel driven by a motor, which flywheel is connected by a crankshaft and a connecting rod to the pump ram such that the pump ram is continuously raised and lowerd through a fixed distance during a forging operation.

3. A forging press as claimed in claim 1 or 2, wherein said oil supply means comprises a check valve connected by duct means to said adjustable cavity and to a reservoir, and a changeover valve which, upon actuation, shuts said check valve.

4. A forging press as claimed in claim 3, wherein said changeover valve is magneti cally actuated.

5. A forging press as claimed in claim 3 or 4, further comprising a projection formed on said flywheel adapted to actuate said changeover valve by contact with a first limit switch, the projection being positioned on the fly-wheel such that it contacts the first limit switch before the pump ram reaches its highest position.

6. A forging press as claimed in claim 5, further comprising a second limit switch for deactuating the changeover valve and opening the check valve upon contact with said projection.

7. A forging press as claimed in any preceding claim, further comprising means for effecting reciprocating motion of the stop means lengthwise of the housing and relative to said laterally protruding member, this means comprising a pulse motor, a geared shaft driven, in use, by the motor, a geared wheel meshing with the geared shaft and comprising an internally threaded intermediate member which is, in use, revolved by the gear, connected to a pusher member of a servo arrangement carrying said stop means whose position is governed by the extent of rotation imparted to the intermediate member.

8. A forging press as claimed in any one of claims 1 to 6, wherein said stop means includes a member whose thickness varies from one edge region to an opposite edge region acting on a further part of the stop means and means for displacing said member in such manner that it causes said displacement of the relative distance between said stop means and said laterally protruding member, in accordance with the thickness of the portion of the said member acting on said further part of the stop means.

9. A forging press as claimed in claim 8, wherein said member is of circular from varying uniformly in thickness from one edge region to a diametrically opposed edge region and the means for displacing said member comprises a geared wheel carrying said member, a rack engaging the geared wheel and means for imparting linear motion to the rack.

10. A forging press, substantially as hereinbefore described with reference to, and as shown in Figures 1 and 2, or Figures 1, 3 and 4 of the accompanying drawings.